Rule 602 specifically exempts expert testimony from this requirement. Rule 602 of the Federal Rules of Evidence requires that a witness only testify if evidence sufficiently supports that the witness has personal knowledge of the facts. Therefore, the major difference between experts and lay witnesses is personal knowledge. not based on scientific, technical, or other specialized knowledge within the scope of Rule 702.helpful to clearly understanding the witness’s testimony or to determining a fact in issue.rationally based on the witness’s perception.Rule 701 of the Federal Rules of Evidence states that if a witness is not testifying as an expert, testimony in the form of an opinion is limited to one that is:

the expert has reliably applied the principles and methods to the facts of the caseĪs to substantive testimony, expert witnesses largely differ from lay witnesses, who are best defined by what they are not – experts.the testimony is the product of reliable principles and methods.the testimony is based on sufficient facts or data.the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue.A court who has designated a witness as an expert may offer testimony if: In substantive aspects, expert witnesses differ from other witnesses in that they are experts qualified “by knowledge, skill, experience, training, or education,” as defined under Rule 702 of the Federal Rules of Evidence.

Expert witness services definition